A near-infrared quantum cutting phosphor GdBO3:Tb3+,Yb3+ shows poor optical absorption in the ultraviolet-visible excitation spectral range and weak near-infrared luminescence in the 900–1100 nm range, which strongly limit its practical application in silicon-based solar cells, due to the inefficient excitation of the Tb3+ ions for their intra-4f forbidden transitions. Herein, Ce3+ ion has been codoped as a sensitizer in GdBO3:Tb3+,Yb3+, thus enlarging the absorption linewidth and increasing the absorption cross-sections in the ultraviolet-visible region. The presence of Ce3+ results in an enhancement in Yb3+ near-infrared emission intensity by a factor of ∼30, which makes these phosphors more attractive as luminescent downconversion materials for enhanced silicon-based solar cell performance. The relevant luminescence and energy transfer mechanisms involved have also been investigated. The present results demonstrate that the 4f-5d luminescence of Ce3+ may be used to sensitize the Tb3+–Yb3+ downconversion process.